There's an issue with this one so I need to add a fix and resubmit (it fails when USB is configured as a module), so please don't accept this yet. However I would like to get feedback on whether or not this new approach looks ok (it includes fixes based on v1 feedback). Thanks. On Tue, 2016-12-13 at 17:22 -0800, Todd Brandt wrote: > The USB resume code in the kernel currently uses a set of hard coded > delay values that are defined in the USB 2.0 spec. Specifically these > three have the most effect on resume time: > > - tdrsmdn: resume signal time (20ms - infinity) usb 2.0 spec 7.1.7.7 > - trsmrcy: resume recovery time (10ms) usb 2.0 spec 7.1.7.7 > - trstrcy: reset recovery time (0ms - infinity) usb 2.0 spec 7.1.7.5 > > These values have been padded considerably in order to accomodate > non-compliant devices. > > - tdrsmdn: resume signal time = 40ms > - trsmrcy: resume recovery time = 10ms > - trstrcy: reset recovery time = 50ms > > I propose that we provide a kernel parameter that sets the USB timing > values to their spec minimums. The following patches do this by creating > a global struct which contains these values. By default the values remain > as they are now, but if usb_timing_minimum=1 is added to the kernel cmd > line they're set to their minimums. This struct can be expanded over time > to include other hardcoded values that have padding we can remove. > > I've created a blog entry on 01.org with some analyze_suspend test > cases illustrating the benefits: > > - https://01.org/suspendresume/blogs/tebrandt/2016/usb-resume-optimization-using-spec-minimum-delays > > Todd Brandt (2): > USB: add switch to turn off padding of resume time delays > USB: usb resume time delay debug > > Documentation/admin-guide/kernel-parameters.txt | 7 +++ > drivers/usb/core/hub.c | 12 ++--- > drivers/usb/core/usb.c | 70 +++++++++++++++++++++++++ > drivers/usb/dwc2/hcd.c | 2 +- > drivers/usb/host/ehci-hcd.c | 4 +- > drivers/usb/host/ehci-hub.c | 6 +-- > drivers/usb/host/fotg210-hcd.c | 2 +- > drivers/usb/host/isp116x-hcd.c | 2 +- > drivers/usb/host/isp1362-hcd.c | 2 +- > drivers/usb/host/ohci-hub.c | 2 +- > drivers/usb/host/oxu210hp-hcd.c | 4 +- > drivers/usb/host/r8a66597-hcd.c | 2 +- > drivers/usb/host/sl811-hcd.c | 2 +- > drivers/usb/host/uhci-hub.c | 6 +-- > drivers/usb/host/xhci-hub.c | 6 +-- > drivers/usb/host/xhci-ring.c | 2 +- > drivers/usb/isp1760/isp1760-hcd.c | 2 +- > drivers/usb/musb/musb_core.c | 6 +-- > drivers/usb/musb/musb_virthub.c | 2 +- > include/linux/usb.h | 23 +++++++- > 20 files changed, 131 insertions(+), 33 deletions(-) > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
